1. Field of the Invention
The present invention relates to an apparatus in which printing is performed by ejecting liquid, and wiping is performed with respect to an ejection port face ejecting the liquid, a wiping method of liquid ejecting head, and a printing apparatus.
2. Description of the Related Art
In recent years, an ink jet printing apparatus has become widely popular. The ink jet printing apparatus makes a printing head scan with respect to a printing medium, and performs printing by ejecting ink droplets from the printing head at the time of this scanning. Such an ink jet printing apparatus is easily downsized, and has advantages such that color printing can be performed relatively simply.
When the printing is performed in such a way that the ink is ejected from the ink jet printing apparatus, a small amount of ink having failed to become the ink droplet among ink ejected from the ejection port may float between the ejection port and the printing medium in a misty state. Furthermore, the ink may be splashed when impacted against the printing medium, and the ink splashed may float between the ejection port and the printing medium in a misty state. Hereinafter, the mist of ink floating between the ejection port and the printing medium is called “ink mist”. There is a concern that the ink might block a part of the ejection port or all of the ejection port in such a manner that such an ink mist adheres around the ejection port. And there is a concern that the ink cannot be ejected when the ink has blocked the ejection port. Furthermore, there is a concern that a failure that an impacting accuracy of the ink decreases or the like might occur when an ejecting direction of the ink is changed by the ink having covered the ejection port, and that the ink cannot impact a predefined location even when the ink can be ejected. Additionally, when the ink mist is generated and adheres around the ejection port, a state in which a vicinity of the ejection port becomes damp by the adhered ink mist is produced. Accordingly, there is a possibility that foreign matter such as paper powder, dust or the like floating between the ejection port and the printing medium might easily adhere around the ejection port due to the wet condition of the ejection port. When such foreign matter adheres around the ejection port, there is a concern that ejecting miss or ejection failure might occur in the same way that the ink mist covers the ejection port in such a state that the adhered foreign matter covers the ejection port.
Accordingly, for keeping a periphery of the ejection port in good condition, a recovery operation periodically removing the ink or the foreign matter which adheres around the ejection port is performed. As a recovery member performing the recovery operation in the ink jet printing apparatus, for example, a wiping mechanism having a blade or the like at a main scanning direction end of the printing head in the ink jet printing apparatus may be sometimes arranged. And then, when a state in which the wiping is required occurs, the printing head is transferred to a location at which the wiping mechanism is arranged, and the wiping is performed in such a way that the printing head is wiped by the wiping mechanism. In such an ink jet printing apparatus, when the printing head and the blade move relatively, the blade wipes an area around the ejection port, and at this time, the foreign matter or the ink which adheres around the ejection port is rubbed and stuck to the blade side. Accordingly, the foreign matter or the like is wiped and removed from a periphery of the ejection port.
Furthermore, with respect to ink increased viscosity or other foreign matter which is hard to completely remove even by such a wiping manner, it is solved by periodically performing a suction operation to absorb the ink from the ejection port by a negative pressure generated by a pump after capping the ejection port face. Additionally, for the recovery operation in addition to this, after capping the ejection port face, a preliminary ejecting operation which ejecting the determined amount of ink may be sometimes performed separately with respect to a process of ejecting the ink for printing.
With regard to the wiping mentioned above, a control executing the wiping when an adhering condition of the ink near the ejection port reaches a determined state is sometimes employed. By employing such a method, the wiping can be performed efficiently without decreasing throughput, and the ejection can be kept in excellent condition. With regard to such method, for example, in Japanese Patent Laid-Open No. 1995-125228, a method of determining a timing executing the wiping has been proposed by employing timing measurement by a timer and a counting of ink ejecting frequency from the printing head (dot count). Furthermore, in Japanese Patent Laid-Open No. 2001-121717, a method of determining a timing executing the wiping in combination with a normal dot count and measurement of printing duty is disclosed. Additionally, in Japanese Patent Laid-Open No. 2006-240177, a method of determining a timing executing the wiping in combination with the normal dot count and a measurement of generation condition of the ink mist according to the type of ink is disclosed.
However, some ink jet printing apparatuses perform an ejection of the ink by a so-called time sharing drive by which the timing ejecting the ink is shifted for each ejection port with respect to the printing head having a plurality of ejection ports. Accordingly, a maximum consumption power used for one time ejection can be kept low in such a way that a drive timing of ejection energy generating element corresponding to the ejection port is scattered by shifting the ejection timing of the ink.
However, there is a possibility that a problem might occur by shifting the timing of the ejection of the ink accordingly. There is a concern that among two ejection ports adjacent to each other, when the ink is ejected from the one ejection port before the other ejection port ejects the ink, a vibration of the ink within the one ejection port might be transmitted to the other ejection port. In this case, there is a concern that a meniscus of the ink within the other ejection port becomes unstable, which may cause ink ejecting from the ejection port to become unstable, consequently, the ink mist might be generated at the time of its ink ejection.
With respect to such a problem, an interval at which mutually adjacent ejection ports eject the ink is sometimes shortened so that the adjacent ejection ports may not interfere with each other. Accordingly, the ink can be ejected from the one ejection port before a pressure fluctuation of the other ink of the mutually adjacent ejection ports is transmitted by shortening the interval of the ink ejection. Accordingly, generation of the ink mist can be suppressed at the time of the ink ejection.
Furthermore, depending on the type of printing image or the like, there is sometimes a case that a solution in which the ejecting interval of the ink ejected from the mutually adjacent ejection ports is changed variously is thought to be preferable. For example, when an image such as a longitudinal ruled line is formed, it is preferable to make the ink ejecting interval from the mutually adjacent ejection ports relatively long.
However, when an interval of drive timing between the ejection energy generating elements arranged at a location corresponding to the adjacent ejection port can be adjusted accordingly, the amount of generation of the ink mist by the ejection of the ink becomes unstable. Accordingly, the amount of generation of the ink mist becomes variable depending on an operation in which the interval of the drive timing between the ejection energy generating elements arranged at the location corresponding to the adjacent ejection port is adjusted and varied. With respect to the amount of generation of the ink mist correspondingly variable, an operation in which the wiping is performed at a fixed timing as with a conventional manner cannot efficiently remove the ink adhered around the ejection port. When the amount of generation of the ink mist increases in such a way that the interval of the drive timing between the ejection energy generating elements arranged at the location corresponding to the adjacent ejection port is set long, and wiping frequency is set too low in connection with this, there is a concern that ejection failure might occur. Specifically, there is a possibility that the ejection of the ink could not be performed because the ink adhered around the ejection port covers the ejection port, or the impact accuracy of the ink might become low. Furthermore, the amount of generation of the ink mist decreases in such a manner that the interval of the drive timing between the adjacent ejection energy generating elements is set short, and regardless of this, unnecessary wiping is performed, consequently, wiping frequency is thought to be too high. In this case, there is a concern that the throughput of the printing might become low because the printing takes much time by unnecessary wiping operation.